The invention obtains a grounding device such that it is possible to open a path, either instantaneously when a complete ground fault occurs between a ground fault point and a ground wire between a solar cell and an inverter, or otherwise when an incomplete fault occurs therebetween, or to have an alert be issued by operation being continued. The grounding device comprises: an inverter (3) that receives DC power input from a solar cell (1) via DC positive-side and DC negative-side output bus bars (11), (12), carries out an AC power conversion of same, and supplies the AC power to an AC power system (8) via an insulated transformer (10); a circuit breaker (21) that is connected to both (11) and (12), and that is capable of opening an electrical path between (1) and (3) when current flowing though the circuit exceeds a first safety setting value; a grounding line (25), between (3) and (21), which connects either (11) or (12) to a ground (26); a current detector apparatus (23) that detects the current flowing through (25); a fuse (22) that is inserted in series in a portion of (25), and that blows when a complete ground fault state occurs, in which the current flowing through (25) exceeds a detected current level that would not destroy (23) and exceeds the first safety setting value; and a determination apparatus (24) that issues an open operation instruction to (21) when the detected current value detected by (23) exceeds the first safety setting value of (21).